Telephone-exchange system



H. W. ULRICH.

TELEPHONE EXCHANGE SYSTEM. APPLICATION FILED MAY1I,1918.

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Patented Apr. 20, 1920.

UNITED STATES PATENT OFFICE.

HORACE W. ULRICH, Oi EAST ORAIEGE, NEVT JERSEY, ASSIGNOR TO WESTERNELECTRIC COMPENY, INCORPQRATED, 6F NEE/ YORK, N. Y A CORPORATION OE NEWYORK.

TELEPH ONE-EX CHANG-E SYSTEM.

assass n Application filed May 11, 1918.

To a "whom it may cont-cm.

Be it known that I, Henson "W. ULRICH, a citizen of the United States,residing at East Grange, in the county of Essex, State of New Jersey,have invented certain new and useful Improvements in Telephone EX-change Systems, of which the following is a full, clear, concise, andexact description.

This invention relates to telephone eX- change systems, and morevparticularly to such systems employing trunk circuits for completingconnections between telephone lines terminating at differentswitchboards.

in object of this invention is the provision of improved signaling meansfor such systems.

In accordance with this invention, a trunk circuit is provided with asignal control relay whose operating circuit is partially establishedupon connection being made with the incoming end of the trunk circuit,and is coi'upletcly established upon the disconnection of a linl:circuit from the outgoing end, thereby to cause the operation of asignaling device associated with the link circuit connected with theincoming end.

For a more complete understanding of this invention, reference should behad to the following description considered in connection with theaccompanying drawing illustrating one embodiment thereof.

As shown in the drawing, a telephone line A extends to and terminates ata switchboard at which is located a link circuit B, which may beconnected with the telephone line A in any suitable and well-knownmanner. A trunk circuit C extends from this first switchboard to asecond switchboard at which is located a link circuit D for estabishingconnections between the trunk circuit C and a telephone line Eterminating at the second switchboard. The link circuits B and D may, ofcourse, be employed for interconnecting telephone lines similar to thosewhich are shown terminating at the respective switchboards. Theapparatus shown to the left of the dotted line 1-1 is located at thefirst switchboard which may be designated as X, and that shown to theright of this dotted line may be located at the second switchboarddesignated as Y.

The operator at switchboard X having actuated the listening key 6 toconnect the telephone set with the calling telephone line Specificationof Letters Patent.

Patented Apr. 20, 1920.

Serial No. 233,824.

A, receives instructions that connection is desired with a telephoneline, for example, line H, which terminates at the switchboard Y. Thelistening key 6 may then be restored to normal position and plug 7 ofthe cord circuit B inserted in jack 8 of the trunk circuit C. Lamp 9lights, and relay 10 and cutoti' relay 1?) operate ov r a circuit frombattery through the lamp 9, winding of re lay 10, sleeve contacts of theplug 7 and the jack 8, and the winding of cutoff relay to ground. Relay10, in operating, causes the energization of ringing relay 11 ov r acircuit from battery through resistance 12, winding of ringin relay 11,normal contact of relay 16, contact of trip relay 13 and the contact ofrelay 10 to ground. Ringing rell, upon being energized, connects thesource of ringing current 14 with the trunk circuit for causing theoperation of relay 56 over a circuit from the source of ringing current14.- through the winding of trip relay 13, lower alternate contact ofringing relay 11, ring contacts of the plug 7 and the jack 8, lowernormal contact of relay 17, condenser 18, normal contactand winding ofrelay 56, the lower contact of relay l9 and resistance to ground. Relay56, in op erating, completes a locking circuit for itself from batterythrough the upper alternate contact and windin of relay 16, the lowercontact of relay l9 and resistance 20 to groin d. The operation of relay56 also causes lamp 21 to be lighted to furnish a si nal to the operatorat the switchboard Y. 1 operation of the cutoff relay 15 disconnectsline relay 22 from bridged relation to the talking conductors of thetrunk circuit C.

The operator at switchboard Y, upon obsewing the lighted condition ofthe lamp 21, inserts plug 23 of cord circuit D into jack 2% of the trunkcircuit C, whereupon relay 1S! and marginal relay 25 operate over acircult from battery through lamp 26, normal contact of supervisoryrelay 27, sleeve contacts of the plug 23 and the jack 24, and thewindings of relays 19 and 25 to ground. The operation of relay 19 opensits lower contact, thereby releasing relay 56 to extinguish the lampZl.The closure of the lower contact of relay 25 connects resistance 28 inseries with supervisory relay 29. to provide a low impedance path forringing current for causing the operation of trip relay 13. This circuitmay be traced from the source of ringing current 14: through the windingof trip relay 13, lower alternate contact of ringing relay 11, ringcontacts of the plug '7 and the jack 8, lower normal contact of relay17, winding of supervisory relay 29, lower contact of relay 25,resistance 28 and the upper normal contact of relay 17 to ground. Triprelay 18, upon operating, opens the short circuit about the winding ofrelay 16, which in turn is energized to open its normal contact in thepreviously mentioned short circuit, and to close its alternate contact,thereby establishing a short circuit about the winding of ringing relay11 and providing a locking circuit for itself. Ringing relay 11immediately releases its armatures, disconnecting the source of ringingcurrent 14 from the trunk circuit. I

Upon the closure of the normal contacts of ringing relay 11, supervisoryrelays 29 and 33 operate over a circuit from battery through the windingof supervisory relay 33,

lower normal contact of ringing relay 11, ring contacts of the plug '7and the acl; 8, lower normal contact of relay 17, winding ofisupervisoryrelay 29, lower contact of relay 25, resistance 28 and the upper normalcontact of relay 17 to ground. Superrisory relay 33, in operating,establishes shunt circuit including resistance 12 about the lamp 9,thereby extinguishing lamp. Supervisory relay 29, in operati opens theshort circuit about the winding of relay 17, whereupon this relayoperates oi'er a circuit from battery through the upper contact of relay19, resistance and the wind ing of relay 17 to ground. Upon theoperation of relay 17, the normal contacts thereof are opened, and thealter ate contact closed, whereupon supervisory r lays 33 and 29 aremaintained energized over a circuit from battery through. the winding ofrelay 33, lower normal contact of ringing relay 11, ring contacts of theplug 7 and the jack 8, lower left-hand winding of repeating coil 35,winding of supervisory relay 29, lower contact of relay 25, resistance28, alternate contact of relay 17, upper lefthand winding of repeatingcoil tip contacts of the jack 8 and the plug 7, and the upper normalcontact of ri gin 11 to ground. The operation oi? re the closure of itsupper contact, eireo partially establishing an operating ('11 n1 forrelay 36. The winding oi this relay 3 is normally short-circuitedthrough tl middle normal contact of relay 1?, and whilrelay 17 isoperated, he short circuit about the winding of relay 36 is maintainerthrough the alternate contact of sin ervisory relay 29, which operatesprior to the operation of relay 17. The insertion or the plug 23 intothe jack 24: also causes the operation (DID GB operator may thereuponactuate 1 of cord and trunk supervisory relays 27 and 37 over a circuitfrom battery through the winding cl supervisory relay 2? contacts of theplug 23 and the 3' lower right-hand winding of the re coil left-hand lowresistance winding 0 the trunk supervisory relay 3?, left-hand contactof relay 86, upper rightl1and winding of repeating coil 35 and the tipcontacts oi? the jack 2% and the plug 23 to ground. The operation oicord supervisory relay 2? removes the short circuit from re sistance S8,and establishes a short circuit for the lamp 26. The resistance of thelamp 26 and the so that the exclusion of one from and the inclusion ofthe ther in the sleeve circuit, has no effect upon the relays 19 and Theoperation of the trunk supervi ory relay 3'? closes its contact which isin multiple with the iowercontact of relay 25.

The operator at switchboard Y may actuate listening key 39 to connectthe o ators telephone set in circuit. The a ises the tion of thislistening hey at sure of the middle contact thereof, whereupon marginalrelay 25 releases its armatures. This is brought about by includingresistance 41 in parallel with the windi g of relays 19 and :25, uponthe closure of thmiddle contact of the listening lrey 39.

release of this marginal relay 2:? at this ti has no effect upon theapparatus of the trunk circuit. The reason for releasing this relay 2. 3when the listening key 39 is actuated will more fully hereinafterappear.

llpou being advised that connection is desired with the line of subsciber E, the operator at the switchboard restores the listening key 39 tonormal cond'tion, whereupon marginal relay 25 attracts its armatures.The operator may then insert calling plug of the cord circuit D intojack to of the telephone line E, whereupn c lin supervisory lamp l?lights an d c o t off rel ay a8 operates over acircuit from batterythrough the lamp ll, normal rontact oi the calling supervisory relaylf), sleeve conlti. and

tacts of the plug 4.5 and the jack the winding of cutoii relay li-8 toThe operation of the nects the line relay "from the 51' to connect thesource of ringing current with the line for operating the usual cal bellat the station. Upon the removal oi: the receiver by subscriber inresponse to the operation of the call bell, sup relay 41-9 is operatedto open the six about resistance 52 and to est 1 circuit for the lamp4-? which tiuguished. versat'h, the subscribers restore v ers to theswitchhoolzs, thereby can ing the appropriate supervisory lamps of theassoesistance coil So are about equal,

ciatecl cord circuits to furnish disconnect signals to the operators.The operators may thereupon Withdraw the plugs from the jacks restoringall apparatus to normal con clition.

' the operator at switchboard Y does not aituate th listening key 39, a'ter inserting the plug into the eel: es, the answering operaterstelephone set will not be connected in ci iit Wl en he originating oper-'s connected in circuit by the actuion of the listening key 6. it willbe necessary, therefore, for the originating operator to rering orresignal the answering 5 operator This may be done by witliclrawing theplug 7 rroni and reinserting i into the l The uuthdrawai of the plug Tjac i 8.

:"rom the jacl-c 8 causes the restoration of all the aoparatus the certcirc it, and the ct cutofi relay l5 and supervisory relay of the trunkcircuit. Relay 29, in

using its armature, opens the short cireuit about the winding of relay36, which weupon operates over a circuit from batthrough the uppercontact of: in nal resistance and the winning oi 2-3-8 to ground. Relay36, in 01 er-iting,

Jens its contacts. The opening of the lit-hand contact prevents thereestablish- 30 it ot the short circuit about its Winding n snpeuisoryrelay 29 again operates.

of the le'tt-hancl contact ot a opens the shor circuit about the itlereby increasingthe resistance in with the cord supervisory relay ordsuiervisory relay 2. thereupon re- 5 its arinatures n the lamp to removethe short cir- 26, and to establish a resistance 38.

' "lit" to T he uruish a signal to rater Qhe reinsertion of the jack 8causes the open i0 illt'l ll of the cord cirthe source of ringing curn'ii' hereupon trip es causing the li iich releases ingin cur- Sugervisorypen operate. he tol'iboard Y, oliiseri'ing i oi": the lamp actu- 9 toconnect tle operset at in circuit. The clone niiclclle contact of thislisteireleases marginal relay 25., which 'ts upper conoict causes relarl pon the nosure t of relay 86, the aiout the winding thereof is "Giffestablished. The closure if the L'Ulliliiflb of relay 36 short-circuitsresistance winding of the trunk 65 -Z Z}:)GT,1S )F:: relay to cause theoperation the rile systein comprisfrom a first e he he second sivitihioperating ishecl upon ,econil link circuit il nieans rcspo Ive linl:circuit {G the hone hange syst uit extending sece suutchboarih a link civuit ,1 su'itchhoarc, a signaiingxlevice at the second switchboardoperated upon conneci with trunk cirsecond switch the trunk circuit i- 3ing the chang N i -v XiHhll i iboaiwl a ll swi' e c rcrating ciruit imeans responsive to the connection or second nlt circuit with. the trunkcircuit ior l act in the "i circuit, e to the {LL Jenner of the LL- '1'-L iiQiIl M16 blllil ulLbillu O iesi tance rcui thereby to ll and a sig asignal contri l therefor partially established 1 nection of the secondlinl: circ trunk circuit, means responsive to the lisconnection of thefirst link cir uit with "he c trunl: circuit for completing thepartially 13 ond switchboard operated upon connection of ringing currentwith the trunk circuit, a link circuit at the second swi chboard, asignal control relay, an operating circuit there for partiallyestablished upon the connection of the second link circuit with thetrunk circuit, means resoonsive to the disconnection oi the first linkcircuit with the trunk circuit for completing the partially establishedoperating circuit, an operators telephone set at the second switchboard,a listening switch for connecting the operators telephone set with thesecond link circuit, and means responsive to the actuation of thelistening switch for causing the opening of the operating circuit.

6. A telephone exchange system comprising trunk circuit extending from afirst to a second switchboard, a link circuit at the first switchboard asource of ringing current, means in the link circuit responsive to theconnection thereof with the trunk circuit for connecting therewith thsource of ringing current, a signaling device at the second switchboardoperating upon connection of the ringing current with the trunk circuit,a link circuit at the second switchboard, a relay in the trunk circuit,a low re sis-tance circuit connected in shunt of the relay, an operatingcircuit for the relay, a relay energized upon connection of the secondlink circuit with the trunk circuit for closing a contact in theoperating circuit, means responsive to the disconnection of the firstlink circuit from the trunk circuit for opening the shunt circuit,thereby to cause the operation 01" the first relay, a signaling devicein the second link circuit operating upon the operation of thefirst-mentioned relay, an operators telephone set at the secondswitchboard, a listening switch for con necting the operators telephoneset with the second link circuit, and a shunt circuit for thesecond-mentioned relay established by the operation of the listeningswitch for causing the release of the second-mentioned relay, thereby toopen the operating circuit of the first-mentioned relay.

7. A telephone exchange system comprising a trunk circuit extending froma first to a second switchboard, a link circuit at the firstswitchboard, a source of ringing current, means in the link circuitresponsive to the connection thereof with t 1e trunk circuit forconnecting therewith the source of ringin current, a signaling device atthe second switchboard operating upon the connection of the ringingcurrent with the trunk circuit, a link circuit at the secondswitchboard, a signal control relay, a second relay in the trunk circuitresponsive to the connection of the second link circuit therewith forcausing the disconnection of ringing current from the trunk circuit, anoperating circuit for the signal control relay partially establisherupon the response or" the second relay, and means responsive to thedisconnection of the first link circuit from the trunk circuit forcompleting the partially established operating circuit.

8. A telephone exchan e system comprising trunk circuit extending from afirst to a second switchboard, a link circuit at the first switchboard,a source of ringing current, means in the link circuit responsive to theconnection thereof with the trunk cir cuit for connecting therewith thesource of ringing current, a signaling device at the second switchboardoperating upon the con nection of the ringing current with the trunkcircuit, a link circuit at the second switchboard, a relay in the trunkcirc iit responsive to the connection of the second link circuittherewith for causing the discomiection of the ringing current from thetrunk circuit, a second relay, an operating circuit therefor partiallyestablished upon the response of the first relay, and a relay responsiveto the disconnection of the first link circuit from the trunk circuitfor completing the partially established operating circuit of the secondrelay, and'a signaling device in the connected second link circuitcontrolled by the second relay.

9. A telephone exchange system comprising a trunk circuit extending froma first to a second switchboard, link circuit the first switchboardconnected with the trunk circuit, a signal control relay in the trunkcircuit, a link circuit at the second switchboard, an operating circuitfor the signal control relay partially established upon the connectionof the second link cir cuit with the trunk circuit, means respon sive tothe disconnection of the first link circuit trom the trunk circuit forcompleting the partially established operating circuit.

10. A telephone exchange system comprising a trunk circuit extendingfrom a first to a second switchboard, a link circuit at the firstswitchboard connected with the trunk circuit, a signal control relay inthe trunk circuit, a link circuit at the second switchboard, a secondrelay in the trunk circuit re sponsive to the connection of the secondlink circuit with the trunk circuit, an operating circuit for the signalcontrol relay partially established upon the response of the second lOOrelay, and a third relay responsive to the disconnection of the firstlink circuit from the trunk circuit for completing the partiallyestablished operating circuit of the signal control relay.

11. A telephone exchange system comprising a trunk circuit extendingfrom a first to a second switchboard, a link circuit at the firstswitchboard connected with the trunk circuit, a signal control relay inthe trunk circuit, a link circuit at the second switchboard, a lowresistance circuit normally connected in shunt of the signal controlrelay, an operating circuit for the signal control relay, a second relayin the trunk circuit responsive to the connection of the second linkcircuit therewith for closing a contact in the operating circuit, and arelay responsive to the disconnection of the first link cir cuit fromthe trunk circuit for opening the normally closed low resistancecircuit, thereby causing the operation of the signal control relay,

12. A telephone exchange system comprising a trunk circuit extendingfrom a first to a second switchboard, a link circuit at the firstswitchboard connected with the trunk circuit, a signal control relay inthe trunk circuit, a link circuit at the second switchboard, a lowresistance circuit normally connected in shunt of the signal controlrelay, an operating circuit for the signal control relay, a second relayin the trunk circuit responsive to the connection of the second linkcircuit therewith for closin a contact in the operating circuit, a relayresponsive to the disconnection of the first link circuit "from thetrunk circuit for opening the normally closed low resistance circuit,thereby causing the operating of the signal control relay, a signalingdevice in the connectec second link circuit operating upon the operationof the signal control relay, an operators telephone set, a listeningswitch controlling the connection thereof with the s cond link circuit,and means responsive to the actuation of the listening switch forrendering the operating circuit ineffective.

in witness wher of I hereunto subscribe my name this 7th day of May, A.D. 1918.

HORACE W. ULnroi-i.

